I doubt they'll reuse the SNK license for Mai a 3rd time, DOA7 would be far ahead of the time cycle for older guests. As much as I like Mai, it is better to change up the guest list to someone else if they are going through the SNK list again. Also Mai has been immensely overused in the guest category now including SF lol. Should bring different SNK characters this time.
Taki would be cool though.